Small-bore refers tocalibers with a diameter of .32 in (8.1 mm) or smaller.[1] It may also refer to small-bore rifle competition. The medium-bore refers to calibers with a diameter between .33 in (8.4 mm) up to .39 in (9.9 mm) and large-bore refers to calibers with a diameter of .40 in (10 mm) or larger.[2]Miniature bore refers historically to calibers of .22 in (5.6 mm) or smaller.
There is much variance in the use of the term small-bore, which over the years has changed considerably with anything under .577 in (14.7 mm) caliber considered small-bore prior to the mid-19th century.[3]
Small-bore competition often refers to shooting competitions conducted with.22Rimfire target rifles.[4][5]